The Venetian blind is made of a number of slats that can be set together at any angle to regulate the light and the air to pass through, or be drawn up together to the top of the window by means of cords. The angle of the slats is adjusted by a modulating mechanism in conjunction with an adjustment rod.
As shown in FIG. 1, the conventional modulating mechanism is mounted in the upper rail of the Venetian blind such that the worm rod 2 is slantingly engaged with the gear 3, so as to prevent the adjustment rod 1 from interfering the slats. The worm rod 2 is thus jutted out of the upper rail such that one end of the worm rod 2 is kept a distance away from the slats, thereby enabling the adjustment rod 1 and the slats to separate from one another. However, the portion of the worm rod 2 that is jutted out of the upper rail is apt to interfere with the slats located in proximity of the upper rail at the time when the slats are drawn up together to the top of the window. In addition, the worm rod 2 is vulnerable to breakage in the course of transportation of the Venetian blind. Moreover, the conventional modulating mechanism described above is apt to complicate the packaging of the Venetian blind.